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Journal of Materials Science & Technology 2024年第3期170卷 246-254页

作者： Ze Pu Wang WenHong Ruan MinZhi Rong MingQiu Zhang Key Laboratory for Polymeric Composite and Functional Materials of MOE GD HPPC LabIGCMESchool of ChemistrySun Yat-Sen UniversityGuangzhou 510275China

To tackle the challenge of producing highly filled polymer composites using the traditional injection molding technique,which is characterized by the fairly high melt viscosity that makes mold filling difficult,the authors propose a solution based on dynamic covalent chemistry.As demonstrated by the proof-of-concept experiments,the 4-arm starshaped polycaprolactone(PCL)oligomers and microcrystalline cel-lulose(MCC)are crosslinked by the reversible Diels-Alder(DA)bonds.The flowability of the compounds greatly decreases due to the dissociation of the intercomponent DA bonds at the retro-reaction tempera-ture,and the networked architecture is reconstructed during cooling as a result of the forward DA reaction.Consequently,the high-loading MCC fillers are well distributed in the matrix and covalently bonded to the nearby PCL,forming a striking contrast to the control in which linear PCL acts as the matrix.The DA bonds crosslinked biodegradable PCL composites exhibit decent mechanical strength(20.7 MPa)even at the MCC fraction of 65 wt%,which is superior to those(5-12.2 MPa)of the highly filled PCL composites(with filler contents of 50-63.8 wt%)reported so far.The proposed approach has sufficient expansibility for the fabrication of the highly filled polymer composites constructed by other types of matrix and fillers.

关键词： Polymer composites Microcrystalline cellulose Polycaprolactone injection molding Dynamic reversible chemistry

Micro powder injection molding of boron carbide components with SiC-Al_(2)O_(3)-Y_(2)O_(3)sintering additives

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Chinese Journal of Aeronautics 2022年第5期35卷 429-440页

作者： Changrui WANG Zhiyou LI Wei TIAN Yuxian LI Lina TANG Qilong PANG Minghe CHEN National Key Laboratory of Science and Technology on Helicopter Transmission Nanjing University of Aeronautics and AstronauticsNanjing 210016China Ji’nan Technician College Jinan 250000China Shanghai Aerospace Equipments Manufacturer Co.Ltd. Shanghai 200245China College of Mechanical and Electrical Engineering Nanjing Forestry UniversityNanjing 210037China

Sintering additives and micro-powder injection molding offer an effective method to densify boron carbide(B_(4)C)and make B_(4)C components with complex shapes.By adjusting the proportion of three kinds of powders(SiC,Al_(2)O_(3)and Y_(2)O_(3)),four kinds of sintering additives were prepared.The feedstock uniformity,debinding behavior,phase composition and microstructure of micro injection molded B_(4)C components with different sintering additives were studied.The results showed that the defects such as lattice distortion and vacancy were introduced into ball milling,which increase the surface energy and benefit subsequent sintering densification.The feedstock had good uniformity and rheology that met the requirements of micro powder injection molding.After debinding,B_(4)C components had enough strength and showed certain sintering characteristics.The addition of sintering additives was beneficial to densification and sintering temperature reduction.The addition of sintering additives formed a second phase in the B_(4)C crystal and at the grain boundary of B_(4)C crystal,which changed the fracture mode from transgranular fracture to mixed fracture mechanism with transgranular fracture.

关键词： Composite materials Fracture injection molding Microstructure Phase composition

In-situ density measurement for plastic injection molding via ultrasonic technology

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Frontiers of Mechanical Engineering 2022年第4期17卷 217-228页

作者： Zhengyang DONG Peng ZHAO Kaipeng JI Yuhong CHEN Shiquan GAO Jianzhong FU State Key Laboratory of Fluid Power and Mechatronic Systems College of Mechanical EngineeringZhejiang UniversityHangzhou 310027China Key Laboratory of 3D Printing Process and Equipment of Zhejiang Province College of Mechanical EngineeringZhejiang UniversityHangzhou 310027China Beijing Institute of Aeronautical Materials Beijing 100095China Haitian Plastics Machinery Group Co. Ltd.Ningbo 315801China

Density variation during the injection molding process directly reflects the state of plastic melt and contains valuable information for process monitoring and optimization.Therefore,in-situ density measurement is of great interest and has significant application value.The existing methods,such as pressure−volume−temperature(PVT)method,have the shortages of time-delay and high cost of sensors.This study is the first to propose an in-situ density measurement method using ultrasonic technology.The analyses of the time-domain and frequency-domain signals are combined in the proposed method.The ultrasonic velocity is obtained from the time-domain signals,and the acoustic impedance is computed through a full-spectral analysis of the frequency-domain signals.Experiments with different process conditions are conducted,including different melt temperature,injection speed,material,and mold structure.Results show that the proposed method has good agreement with the PVT method.The proposed method has the advantages of in-situ measurement,non-destructive,high accuracy,low cost,and is of great application value for the injection molding industry.

关键词： ultrasonic measurement melt density in-situ measurement injection molding

injection molding and debinding of micro gears fabricated by micro powder injection molding

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International Journal of Minerals,Metallurgy and Materials 2013年第1期20卷 82-87页

作者： Xin-lei Ni Hai-qing Yin Lin Liu Shan-jie Yi Xuan-hui Qu School of Materials Science and Engineering University of Science and Technology Beijing School of Mechanical and Electrical Engineering China University of Mining and Technology (Beijing)

Micro powder injection molding （μPIM） was investigated for possible mass production of micro-components at rela- tively low cost. However, scaling down to such a level produces challenges in injection molding and debinding. Micro gears were fabricated by μPIM from in-house feedstock. The effect of injection speed and injection pressure on the replication of the micro gear cavity was investigated. Solvent debinding and thermal debinding processes were discussed. The results show that micro gears can be successfully fabricated under the injection pressure of 70 MPa and the 60% injection speed. Either too low or too high injection speed can cause incomplete filling of micro gears. The same is the case with too low injection pressure. Too high injection pressure can bring cracks. Solvent debinding of micro gears was performed in a mixture of petroleum ether and ethanol. Subsequently, micro gears were successfully debound by a multistep heating schedule.

关键词： gear manufacture micro gears injection molding debinding zirconia

Intelligent methods for the process parameter determination of plastic injection molding

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Frontiers of Mechanical Engineering 2018年第1期13卷 85-95页

作者： Huang GAO Yun ZHANG Xundao ZHOU Dequn LI State Key Laboratory of Material Processing and Die & MouldTechnology Huazhong University of Science and Technology Wuhan430074 China

injection molding is one of the most widely used material processing methods in producing plastic products with complex geometries and high precision. The determination of process parameters is important in obtaining qualified products and maintaining product quality. This article reviews the recent studies and developments of the intelligent methods applied in the process parameter determination of injection molding. These intelligent methods are classified into three categories： Case-based reasoning methods, expert sys- tem-based methods, and data fitting and optimization methods. A framework of process parameter determination is proposed after comprehensive discussions. Finally, the conclusions and future research topics are discussed.

关键词： injection molding intelligent methods,process parameters optimization

Optimization of Processing Parameters for Minimizing Warpage of Large Thin-walled Parts in Whole Stages of injection molding

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Chinese Journal of Polymer Science 2014年第11期32卷 1535-1543页

作者：温彤 Xia Chen Chen Yang Lan-tao Liu Liang Hao College of Materials Science and Engineering Chongqing University College of Engineering Mathematics and Physical SciencesUniversity of Exeter

This study investigated total warpage of a type of motorcycle seat support made of polypropylene（PP） during the entire process of injection molding and free-cooling after demolding. Finite element modeling（FEM） analysis for injection molding and its associated thermal deformation was carried out in the study. The effects of processing parameters on warpage occurring in different stages were analyzed by Taguchi optimization method. It was found that packing pressure is the major factor that affects warpage in the injection stage, whereas cooling time is the major factor in free-cooling stage. From an overall evaluation, melt temperature affects the total warpage most, followed by cooling time, packing pressure, packing time and mold temperature. The result proved that optimum parameters for minimizing final warpage of the injected parts can be obtained only when the deformation in the entire manufacturing process is addressed in both molding and demolding stages.

关键词： injection molding Warpage Demolding Numerical simulation Taguchi optimization method.

Gate design and filling process analysis of the cavity in injection molding process

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Advances in Manufacturing 2016年第2期4卷 123-133页

作者： Mehdi Moayyedian Kazem Abhary Romeo Marian School of Engineering University of South AustraliaMawson Lakes Campus Adelaide SA 5006 Australia

This paper presents a new geometry of an edge gate in the injection molding process called modified edge gate. The corners of current edge gate result in the turbu- lence of molten plastic into the cavity which leads to internal and external defects. The aim of the new geometry is to reduce the internal and external defects of injected part such as sink marks and short shot. The easier de-gating analysis for the new geometry to decrease the visible blemish of the injected part was proposed in this study. A modified edge gate was proposed for two circular fiat plates with thickness 1 ram. Finite element method （FEM） was used along with SolidWorks plastic. Internal and external defects of the injected part were analyzed via SolidWorks plastic. To validate the new geometry, an experimental study was implemented for two polypropylene （PP） cir- cular fiat plates with modified edge gate to confirm the simulation results. The contribution of this research is to modify the geometry of current edge gate by removing the corners of rectangular edge gate which leads to the reduction of scrap. The new geometry presents easier de- gating of gate and less visible blemish of the injected part. A smooth flow of molten plastic into the cavities reduces the internal and external defects. The outcome of this study demonstrates filling of the cavities with no short shot. In addition, no sink marks were detected with modified edge gate. Finally, the modified blemish on the injected part edge gate. edge gate has in comparison less visible with current edge gate.

关键词： injection molding Gate design Internaldefects External defects

The Simulation and Optimization of Aspheric Plastic Lens injection molding

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Journal of Wuhan University of Technology(Materials Science) 2005年第2期20卷 86-89页

作者：温家伶 School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Assoc.Prof

For the purpose of reducing the volumetric shrinkage and volumetric shrinkage variation, the process in injection molding of aspheric plastic lens was simulated, and several process parameters which include holding pressure, melt temperature, mold temperature, fill time, holding pressure time and cooling time were optimized by using an orthogonal experimental design method. Finally, the optimum process parameters and the influence degree of process parameters on the average volumetric shrinkage and the volumetric shrinkage variation are obtained.

关键词： injection molding volumetric shrinkage volumetric shrinkage variation orthogonal experimental design

Optimization of injection molding Process of Bearing Stand Based on BP Network Method

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Transactions of Nanjing University of Aeronautics and Astronautics 2014年第2期31卷 180-185页

作者：虞俊波周小林邓常乐刘军王骥 School of Mechanical Engineering & Mechanics Ningbo University Ningbo 315211 P.R. China Ningbo Furja Industrial Corporation Limited Ningbo 315400 P.R. China

The quality of injection plastic molded parts relates to precise geometry,smooth surface,strength,durability,and other indicators that are associated with the mold,materials,injection process,and service environment.The warpage is one of main defects of injection products,which cost much time and materials.In order to minimize warpage to ensure the precise shape of molded parts,it needs to combine design,service conditions,process parameters,material properties,and other factors in the design and manufacturing.Finite element tools and material database are used to analyze the occurrence of warpage,and analysis results contribute to the improvement and optimization of injection molding process of typical parts.To find the optimal process parameters in the solution space,experimental data are used to establish backpropagation(BP)network for predicting warpage of a bearing stand based on analysis with Moldflow.With a proper transfer function and the BP network architecture,results from the BP network method satisfiy the criteria of accuracy.The optimal solutions are searched in the BP network by the genetic algorithm with the finding that the optimization method based on the BP network is efficient.

关键词： injection molding orthogonal test Moldflow BP neural network warpage deflection

Novel Plastic Encapsulation Holding Method for Automobile Glass Using injection molding Process

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Journal of Donghua University(English Edition) 2014年第1期31卷 67-71页

作者：刘琼王乾廷 School of Materials Science and Engineering Fujian University of Technology

Glass positioning and holding is difficult in the process of injection molding encapsulation of automobile glass. A suction cup or soft resin is always introduced in this process. However,these materials cannot hold glass tightly,thus resulting in the unsteady quality of toughened glass and encapsulated plastic. To solve this problem,a novel holding method called magnetic high-pressure holding with twin bags is proposed to address the features of toughened glass and the encapsulation injection process. Firstly,a pair of permanent magnets is introduced as energy source,followed by the magnetization of a couple of magnetic particle bags. Contact between the single bag and the glass surface will enable the couple of magnetic particle bags to hold glass tightly and to self-adapt the freeform of the glass. Secondly, an experimental system with mechanical and control systems is designed. This system is controlled by the opening and closing force of the mold,which turns the magnetic field on or off to hold or loosen the glass. The magnetic field distributions are measured at important positions of the permanent magnets and in the magnetized particles in the experiments to determine the holding performance. Finally, the process of determining the parameters of the magnet and its attenuation is analyzed, including the minimum friction force between the glass and the particle bag during injection molding,the magnetic energy product and the magnetized filed distributions,and the re-checking method for these parameters. The theoretical analysis and the experimental result show that this flexible holding system may produce sufficient holding force,which not only protects glass but self-adapts the glass freeform as well. The production practice meets the technical requirements of injection molding with a defect-free surface,with no scratches and cracks on the glass and no slight glass movements in the mold cavity.

关键词： injection molding plastic encapsulation automobile glass magnetized field